The present invention relates to a liquid cooling system which operates by the boiling of a coolant for cooling a high frequency solid state device, such as an amplifier or an oscillator, which comprises a heat generating semiconductor chip, such as a transistor or a diode, for microwave or millimeter waves.
A high frequency solid state device is cooled by a boiling liquid type cooling system in which a liquid coolant is used as a cooling medium. The coolant is heated and boiled by the heat of the solid state device and evaporated to produce vapor bubbles and, thereby the heat of the solid state device being absorbed. The vapor is condensed to liquid and reused as the coolant.
In the liquid cooling system of the prior art, the semiconductor solid state chip is secured on the mount of the solid state device and is exposed and directly contacts the coolant. Therefore, the solid state chip is greatly influenced by the change of dielectric constant of the coolant due to the temperature change thereof, so that the frequency characteristic of the solid state chip is greatly changed. Also, the vapor bubbles generated in the boiling process of the coolant cause unstable change of the dielectric constant thereof, which causes noise of frequency from 0 Hz to 100 Hz along with amplitude modulation of the solid state device due to the noise. Also, waves leaked from the circuit of the solid state device are reflected by the bubbles or liquid surface and back to the solid state circuit, which causes amplitude modulation thereof. Besides the film boiling phenomenon occurs over the entire surface of the solid state chip, since the liquid coolant directly contacts with the chip, which prevents the heat radiation from the chip and causes destruction thereof.